I think it's already seen a resurgence if we're talking about emo in the early 2000's sense of the word. Joshua, Braid, a bunch of Run For Cover bands like Daytrader and Stay Ahead of the Weather. The Get Up Kids came out with a new album, even though it doesn't sound much like their old stuff. Further Seems Forever are playing some shows. Maybe it won't be the comeback trend but it definitely has the chance to be on people's iPods again.